Illuminating apparatus and projecting apparatus

ABSTRACT

An illuminating apparatus includes a condensing optical system for converting light from a light source into convergent light, a first convex lens array for receiving the convergent light, and a collimating optical system for making a plurality of light beams from the first convex lens array parallel to one another. In addition, a polarization converting element array individually converts the plurality of light beams from the collimating optical system into polarized lights.

This application is a continuation of application Ser. No. 09/022,274,filed Feb. 11, 1998 now U.S. Pat. No. 6,257,726.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an illuminating apparatus and a projectingapparatus, and particularly is preferable for a liquid crystal projectorfor projecting the enlarged image of a liquid crystal display element(liquid crystal panel) onto a screen or a wall by a projection lens.

2. Related Background Art

There have heretofore been proposed various liquid crystal projectorsfor illuminating a liquid crystal panel by a light beam from a lightsource, and enlarging and projecting an image based on transmitted lightor reflected light from a liquid crystal panel onto a screen or a wallby a projection lens.

A liquid crystal panel of the TN type which can relatively easily obtainan image of high contrast utilizes the polarizing characteristic ofliquid crystal. Therefore, usually a polarizer and an analyzer areprovided before and behind the liquid crystal panel. Such polarizingfilters have a characteristic of transmitting therethrough polarizedlight of light incident thereon in a particular direction ofpolarization and intercepting polarized light in a direction ofpolarization orthogonal to said direction of polarization. Thus, atleast a half of light from the light source of the liquid crystalprojector is intercepted by the polarizer, and the brightness of aprojected image has been not sufficient.

FIG. 1 of the accompanying drawings is a schematic view of the essentialportions of a projector proposed in Japanese Laid-Open PatentApplication No. 61-90584 which has solved this problem of brightness.

In the liquid crystal projector of FIG. 1, a light beam from a lightsource 201 is made to enter a polarized light separating element 202 forseparating random polarized light into two polarized components(P-polarized light and S-polarized light) orthogonal to each otherthrough an infrared cut filter 208 and a lens 207. A half wavelengthplate 203 is provided in the optical path of the S-polarized light whichis reflected light of a light beam passed through the polarized lightseparating element 202. The direction of polarization of the polarizedlight transmitted through the half wavelength plate is rotated by 90° bythe half wavelength plate and this light is caused to emerge in the sameway as the P-polarized light which is the transmitted light. The opticalpaths of two polarized lights from the polarized light separatingelement 202 are bent and superposed one upon the other on a liquidcrystal panel 205 by the use of a mirror 209 and a prism 204 so that allof the light from the light source 201 can be utilized.

In the liquid crystal projector shown in FIG. 1, the polarized lightseparating element 202 requires the same degree of size as that of thelens 207 or a reflector 206, and this leads to the disadvantage that theprojector becomes bulky and expensive and further, since the light beamis separated into two beams, the illuminating light beam becomes abouttwice as large as that in the prior art, and to enable all of theilluminating light beam to be transmitted through a projection lens, theopening diameter (F_(NO)) of the projection lens becomes two or moretimes that in the prior art, and this also has led to a disadvantage indesigning.

In contrast, in an illuminating apparatus for the liquid crystalprojector of Japanese Laid-Open Patent Application No. 8-304739, apolarization separating element, a bending mirror and a half wavelengthplate are each made into an array to thereby achieve the thinning of apolarization converting portion and moreover, the size of theilluminating light beam is maintained at the same degree as that in theprior art so that a conventional projection lens can be used.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide an illuminatingapparatus of which the polarization converting portion can be madesmaller than in the prior art and a projecting apparatus such as aliquid crystal projector of which the polarization converting portioncan be made smaller than in the prior art.

A first aspect of the present invention is characterized by a condensingoptical system for converting light from a light source into convergentlight, a first convex lens array for receiving the convergent light, acollimating optical system for making a plurality of light beams fromthe first convex lens array parallel to one another, and a polarizationconverting element array for individually converting the plurality oflight beams from the collimating optical system into polarized lights.

A second aspect of the present invention is characterized by acondensing optical system for converting light from a light source intoconvergent light, a collimating optical system for converting theconvergent light into parallel light, a first convex lens array forreceiving said parallel light, and a polarization converting elementarray for individually converting a plurality of light beams from thefirst convex lens array into polarized lights.

What is herein referred to as a convex lens refers to a lens havingpositive refractive power. Accordingly, in the present invention, usecan also be made of a Fresnel lens having positive refractive power or arefractive index division type lens having positive refractive powerwhich does not have a so-called convex surface. Also, what is hereinreferred to as a concave lens refers to a lens having negativerefractive power. Accordingly, in the present invention, use can also bemade of a Fresnel lens having negative refractive power or a refractiveindex distribution type lens having negative refractive power which doesnot have a so-called concave surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an illuminating apparatus according to the prior art.

FIG. 2 is a schematic view of the essential portions of Embodiment 1 ofthe present invention.

FIG. 3 is an illustration of a portion of FIG. 2.

FIG. 4 is an illustration of the optical path of Embodiment 1 of thepresent invention.

FIG. 5 is an enlarged illustration of a portion of FIG. 4.

FIG. 6 is an enlarged illustration of a portion of FIG. 5.

FIG. 7 is an illustration of another embodiment of a portion of FIG. 2.

FIG. 8 is an illustration of another embodiment of a portion of FIG. 2.

FIG. 9 is an illustration of another embodiment of a portion of FIG. 2.

FIG. 10 is an illustration of another embodiment of a portion of FIG. 2.

FIG. 11 is an illustration of another embodiment of a portion of FIG. 2.

FIG. 12 is a schematic view of the essential portions of Embodiment 2 ofthe present invention.

FIG. 13 is a schematic view of the essential portions of Embodiment 3 ofthe present invention.

FIG. 14 is an illustration of the optical path of Embodiment 3 of thepresent invention.

FIG. 15 is an illustration of a portion of FIG. 14.

FIG. 16 is an illustration of another embodiment of a portion of FIG.14.

FIG. 17 is an illustration of another embodiment of a portion of FIG.14.

FIG. 18 is a schematic view of the essential portions of Embodiment 4 ofthe present invention.

FIG. 19 is an illustration of a portion of FIG. 18.

FIG. 20 is an illustration of a portion of FIG. 18.

FIG. 21 is an illustration of the optical path of Embodiment 4 of thepresent invention.

FIG. 22 is a schematic view of the essential portions of Embodiment 5 ofthe present invention.

FIG. 23 is a schematic view of a three-plate type color liquid crystalprojector to which the illuminating apparatus 230 of the presentinvention is applied.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a schematic view of the essential portions of an embodiment ofthe present invention. In FIG. 2, the reference numeral 230 designates apart or the whole of an illuminating apparatus, and the referencenumeral 1 denotes a light source such as a metal halide lamp. Thereference numeral 2 designates a parabolic mirror which is a reflectorof which the reflecting surface comprises a parabolic surface, and thisparabolic mirror reflects a light beam from the light source 1 andconverts it into parallel light, and causes this parallel light to entera lens 3. The lens 3 has positive refractive power.

The reference numeral 4 denotes a first convex lens array comprising aplate having a plurality of lenses 4 a having positive refractive power.The reference numeral 5 designates a concave lens having negativerefractive power. The reference numeral 6 denotes a second convex lensarray comprising a plate having lenses 6 a having positive refractivepower which correspond to the individual lenses 4 a of the first convexlens array 4. The reference numeral 7 designates a polarizationconverting element array having a construction shown in FIG. 3, andcausing incident non-polarized (random-polarized) light to emerge aslinearly polarized light polarized in a particular direction. Thedirections of polarization of polarized lights emerging from therespective polarization converting elements are coincident with eachother as shown in FIG. 3.

The reference numeral 8 denotes a condensing lens having positiverefractive power. The reference numeral 9 designates a condenser lenswhich condenses the illuminating light on a projection lens 11 through apanel 10. The reference numeral 10 denotes an image display elementcomprising a liquid crystal panel. The projection lens 11 has positiverefractive power, and enlarges and projects an image formed by the imagedisplay element 10 onto a screen or a wall.

The concave lens 5 makes a plurality of non-parallel light beams fromthe first convex lens array parallel to one another and parallel also tothe optical axis so that corresponding light beams in the polarizationconverting elements 7 may impinge on only the light receiving portionsof the elements 7.

In the present embodiment, it is desirable that the light source 1 be apoint source of light, but the light source 1 may have an expanse. Whenthe light source 1 has an expanse, an expanse also occurs to each lightbeam from the first convex lens array 4 and therefore, provision is madeof a second convex lens array comprising convex lenses (field lenses)corresponding to the lenses of the first convex lens array 4 which aredisposed near the condensed positions of the light beams by the firstconvex lens array.

In the present embodiment, the first convex lens array 4 is provided inthe optical path of convergent light, whereby the size of a secondarylight source produced thereby is made small and therefore, the size ofthe polarization converting element array 7 can also be made small inconformity with the size of the secondary light source and thus, theouter diameters of the concave lens 5, the second convex lens array 6and the polarization converting element array 7 are made smaller thanthe outer diameter of a condensing mirror, whereby the downsizing of theentire apparatus is achieved.

The construction of the polarization converting element array 7 will nowbe described with reference to FIG. 3. The polarization convertingelement array 7 comprises polarization converting elements arrangedcorrespondingly to the individual lenses 6 a of the second convex lensarray 6, and each element has a polarization separating surface 7 a, areflecting surface 7 b for bending the optical path of S-polarized lightreflected by the polarization separating surface 7 a by 90°, a halfwavelength plate (λ/2 plate) 7 c provided in the optical path ofP-polarized light transmitted through the polarization separatingsurface 7 a or the optical path of S-polarized light reflected by thepolarization separating surface 7 a. In FIG. 3, the λ/2 plates 7 c areprovided in the optical path of S-polarized light reflected by thepolarized light separating surface 7 a.

The optical path of the light from the light source 1 in the presentembodiment will now be described with reference to FIGS. 3 and 4. InFIGS. 3 and 4, the light emitted from the light source 1 is reflectedtoward the image display element 10 by the parabolic mirror 2, becomesparallel light, enters the first convex lens array 4 through the convexlens 3 and is divided into a plurality of light beams, which form aplurality of condensing points within a range smaller than the outerdiameter of the parabolic mirror 2. The concave lens 5 makes theplurality of light beams from the first convex lens array 4 parallel toone another, and uniformizes the directions of the light beams enteringthe polarization converting element array 7, and thereafter directs themto the second convex lens array 6. The light beams transmitted throughthe second convex lens array 6 enter the corresponding polarizationconverting elements of the polarization converting element array 7.

The light beams which have entered the polarization converting elementsare separated into S-polarized light and P-polarized light ( and •) ofwhich the directions of polarization are orthogonal to each other by thepolarization separating surface 7 a, and the S-polarized light ()reflected by the polarization separating surface 7 a is reflected by thereflecting surface 7 b and is transmitted through the half wavelengthplate 7 c, by which it is converted into the light (•) of the samedirection of polarization as the P-polarized light transmitted throughthe polarization separating surface 7 a. Accordingly a plurality oflight beams of the same direction of polarization emerges from thepolarization converting element array 7. The plurality of light beamsfrom the polarized light converting element array 7 are combinedtogether on the image display element 10 by the condensing lens 8 andthe condenser lens 9.

The light beam transmitted through the image display element 10 isdirected to the projection lens 11, by which the image formed by theimage display element 10 is formed on a screen or a wall.

FIGS. 5 and 6 are enlarged illustrations of a portion of FIG. 4. FIGS. 5and 6 show the optical path in an ordinary case where the light beamfrom the light source 1 has an expanse. When the light beam from thelight source 1 has an expanse, the angle of the light emerging from theparabolic mirror 2 becomes non-uniform, and each light beam condensed bythe first convex lens array 4 also creates an expanse and the imagingpoint also expands.

So, in the present embodiment, the directions of a plurality of lightbeams of different directions of travel included in the light beams fromthe respective lenses of the first convex lens array 4 are uniformizedby the action of the lenses 601 of the second convex lens array 6provided near the condensed point of the plurality of light beams fromthe first convex lens array 4 to thereby suppress the expanse of theselight beams.

In the present embodiment, the convex lens 3 and the first convex lensarray 4 may be a lens La1 in which as shown in FIG. 7, they are madeintegral with each other, or only a lens La2 in which as shown in FIG.8, the lenses of the first convex lens array 4 are made eccentric in thecentral direction.

Also, the concave lens 5 and the second convex lens array 6 may be onlya lens La3 in which as shown in FIG. 9, the lenses of the second convexlens array 6 are made eccentric in the peripheral direction. Also, thesecond convex lens array 6 may be provided between the polarizationconverting element array 7 and the condensing lens 8 as shown in FIG.10, or may be only a lens La4 in which as shown in FIG. 11, the lensesof the second convex lens array 6 are made eccentric in the centraldirection.

The present embodiment can be intactly used in a three-plate type liquidcrystal projector using three image display elements 10 for RGB byproviding a color resolving system 101 comprising a plurality ofdichroic mirrors between the condensing lens 8 and the image displayelement 10, and providing a color combining system 109 comprisingdichroic prisms or the like between the image display element 10 and theprojection lens 11, as shown in FIG. 23.

FIG. 12 is a schematic view of the essential portions of Embodiment 2 ofthe present invention. In FIG. 12, the reference numeral 230 designatesa part or the entire illuminating apparatus, and the same elements asthe elements shown in FIG. 2 are given the same reference numerals. Thisembodiment differs from Embodiment 1 of FIG. 2 only in that the lens 3is omitted, and by an elliptical mirror which is a reflector 2 of whichthe reflecting surface comprises an elliptical surface, instead of theparabolic mirror 2, the light beam from the light source 1 placed at thefocus position thereof is converted into a convergent light beam andthis convergent light beam is made to enter the first convex lens array4, and in the other points, the construction of this embodiment is thesame as that of Embodiment 1.

FIG. 13 is a schematic view of the essential portions of Embodiment 3 ofthe present invention. In FIG. 13, the reference numeral 1 denotes alight source such as a metal halide lamp. The reference numeral 2designates an elliptical mirror which is a reflector of which thereflecting surface comprises an elliptical surface. The light beam fromthe light source 1 placed at the focus position of the mirror 2 isreflected and condensed and converted into a convergent light beam bythe mirror 2, and the convergent light beam is made to enter the concavelens 5. The concave lens 5 has negative refractive power.

The reference numeral 4 denotes a first convex lens array comprising aplate comprising a plurality of convex lenses 4 a arranged side by sideand having positive refractive power. The reference numeral 6 designatesa second positive lens array comprising a plate comprising convex lenses6 a arranged side by side and having positive refractive power whichcorrespond to the individual lenses 4 a. The reference numeral 71denotes a polarization converting element array comprising aconstruction shown in FIG. 15, and it converts incident non-polarized(random polarized) light into linearly polarized light polarized in aparticular direction and causes this linearly polarized light to emerge.The reference numeral 8 designates a condensing lens having positiverefractive power. The reference numeral 9 denotes a condenser lens whichcondenses the illuminating light on the entrance pupil (aperture stop)of a projection lens 11 through a liquid crystal panel 10. The referencenumeral 10 designates an image display element comprising a liquidcrystal panel. The projection lens 11 has positive refractive power, andenlarges and projects a projected image formed by the image displayelement 10 onto a screen or a wall.

The construction of the polarization converting element array 71 willnow be described with reference to FIG. 15. The polarization convertingelements of the polarization converting element array 71 are providedcorrespondingly to the individual lenses 6 a of the second convex lensarray 6, and each of these elements has a polarization separatingsurface 71 a, a reflecting surface 71 b for bending the optical path ofS-polarized light reflected by the polarization separating surface 71 a,a first half wavelength plate 71 c provided in the optical path ofP-polarized light transmitted through the polarization separatingsurface 71 a, and a second half wavelength plate (λ/2 plate) 71 dprovided in the optical path of the S-polarized light. Thereby theemergent light beam emerges with its polarized state uniformized.

The optical paths in the present embodiment will now be described withreference to FIGS. 16 and 17. In FIGS. 16 and 17, the light emitted fromthe light source 1 is reflected in a particular direction (a directiontoward the image display element 10) and converted into convergent lightby the elliptical mirror 2, and enters the concave lens 5. The concavelens 5 converts the convergent light into parallel light. The parallellight from the concave lens 5 enters the first convex lens array 4 andis divided into a plurality of light beams by this array 4, and theplurality of light beams enter the second convex lens array 6 whileforming a plurality of condensing points within a range smaller than theouter diameter of the elliptical mirror 2 near the second convex lensarray 6. The plurality of light beams transmitted through the secondconvex lens array 6 enter the polarization converting element array 71.

The light beams which have entered the polarization converting elementsof the polarization converting element array 71 are separated intoS-polarized light and P-polarized light ( and •) of which the directionsof polarization are orthogonal to each other by the polarizationseparating surface 71 a, and the S-polarized light () reflected by thepolarization separating surface 71 a is reflected by the reflectingsurface 71 b and is transmitted through the second half wavelength plate71 d, whereby it is converted into linearly polarized light (/)polarized in an oblique direction and emerges. The P-polarized light (•)transmitted through the polarization separating surface 71 a istransmitted through the first half wavelength plate 71 c, whereby itbecomes linearly polarized light (/) polarized in an oblique direction(the same direction as the S-polarized light) and emerges.

Thereby, a plurality of light beams of which the directions ofpolarization are the same emerge from the polarization convertingelement array 71. The plurality of light beams from the polarizationconverting element array 71 are combined together on the image displayelement 10 by the condensing lens 8 and the condenser lens 9.

The light beam transmitted through the image display element 10 isdirected to the projection lens 11. An image formed by the image displayelement 10 is projected onto a screen or a wall by the projection lens11.

In the present embodiment, the concave lens 5 and the first convex lensarray 4 may be comprised of a lens La5 in which they are made integralwith each other as shown in FIG. 16. Also, they may be comprised of alens La8 in which as shown in FIG. 17, the lenses of the first convexlens array are made eccentric in the central direction.

FIG. 18 is a schematic view of the essential portions of Embodiment 4 ofthe present invention. In FIG. 18, the reference numeral 230 designatesa part or the entire illuminating apparatus, and the reference numeral 1denotes a light source such as a metal halide lamp. The referencenumeral 2 designates an emission mirror which is a reflector of whichthe reflecting surface comprises a parabolic surface, and it reflectsthe light beam from the light source placed at the focus positionthereof and converts it into parallel light, and causes the parallellight to enter a first convex lens array 81 through a concave lens 5.The first convex lens array 81 comprises a plate comprising a pluralityof lenses 81 a arranged side by side and having positive refractivepower.

The concave lens 5 has negative refractive power. The reference numeral6 denotes a second convex lens array. The reference numeral 82designates a polarization converting element array which comprises aconstruction shown in FIG. 19 and converts incident non-polarized(random-polarized) light into linearly polarized light polarized in aparticular direction and causes it to emerge. The reference numeral 8denotes a condensing lens. The reference numeral 9 designates acondenser lens which condenses the illuminating light on the entrancepupil (aperture stop) of a projection lens 11.

The reference numeral 10 denotes an image display element comprising aliquid crystal panel. The projection lens 11 has positive refractivepower, and enlarges and projects a projected image formed by the imagedisplay element 10 onto a screen or a wall.

The construction of the polarization converting element array 82 willnow be described with reference to FIG. 19. The polarization convertingelement array 82 has a plate-like member 82 d comprising surfaces havinga mountain-like shape and flat surfaces, four bar-like prisms 82 b andthree half wavelength plates 82 c, and is constructed with the membersjoined together in such a form that a polarization separating surface 82a is provided on a surface of each bar-like prism 82 b and the halfwavelength plates 82 c are provided in the optical path of S-polarizedlight or P-polarized light separated by the polarization separatingsurface 82 a.

In FIG. 19, the bar-like prisms and the mountain-shaped plate-likemember are joined together with the half wavelength plates 82 cinterposed therebetween so that the half wavelength plates 82 c mayreceive S-polarized light. With such a construction, the polarizationseparating surfaces 82 a are not formed at equal intervals, but yet asshown in FIG. 20 which shows the lenses of the first convex lens array81, the optical axes O of the lenses 81 a are made eccentric relative tothe center of each lens 81 a, whereby it becomes possible to make thecondensing point by each lens 81 a of the first convex lens array 81correspond to the corresponding polarization separating surface 82 a asshown in FIG. 21.

In FIG. 21, the light emitted by the light source 1 is reflected towardthe image display element 10 by the parabolic mirror 2 and is convertedinto parallel light and enters the first convex lens array 81, and isdivided into a plurality of light beams by the array 81, and theplurality of light beams form a plurality of condensing points within arange smaller than the outer diameter of the parabolic mirror 2 near thesecond convex lens array 6. The concave lens 5 converts the plurality oflight beams from the first convex lens array into light beams parallelto one another, and directs them to the second convex lens array 6. Thelight beams transmitted through the second convex lens array 6 enter thepolarization converting element array 82.

The light beams which have entered the polarization converting elementsof the polarization converting element array 82 are separated intoS-polarized light and P-polarized light ( and •) of which the directionsof polarization are orthogonal to each other by the polarizationseparating surface 82 a, and the S-polarized light reflected by thepolarization separating surface 82 a is reflected by the reflectingsurface 82 c and is transmitted through the half wavelength plate 82 c,whereby it is converted into linearly polarized light polarized in thesame direction as the P-polarized light transmitted through thepolarization separating surface 82 a, and emerges from the polarizationconverting element array 82 as a plurality of linearly polarized lightsof which the directions of polarization are the same. The plurality oflight beams from the polarization converting element array 82 arecombined together on the image display element 10 by the condensing lens8 and the condenser lens 9.

The light beam transmitted through the image display element 10 isdirected to the projection lens 11. An image formed on the image displayelement 10 is projected onto a screen or a wall by the projection lens11.

FIG. 22 is a schematic view of the essential portions of Embodiment 5 ofthe present invention. This embodiment differs from Embodiment 4 of FIG.18 only in the shapes of a second convex lens array 91 and apolarization converting element array 92 and in that a polarizing plate93 is disposed between the condenser lens 9 and the image displayelement 10, and in the other points, the construction of this embodimentis the same as that of Embodiment 4. Here, the polarization convertingelement array 92 is made just half the array 82 in Embodiment 4 withrespect to the direction of the array.

The polarization converting element array 92 in the present embodimentdoes not correspond to all of individual lenses constituting the secondconvex lens array 91, but effects the polarization conversion of only alight beam passing through the row of lenses in the central portion ofthe second convex lens array 91. Since the intensity of the parallellight beam from the parabolic mirror 2 concentrates in the centralportion, a polarization converting system for converting only thecentral portion of the parallel light beam into predetermined linearlypolarized light is provided so that most of the parallel light of whichthe polarization is random may be converted into linearly polarizedlight.

At this time, in the second convex lens array 91, the size a21 of thecentral lens for receiving the light in the central portion whicheffects polarization conversion is set larger than the size a22 of thelenses in the peripheral portion, whereby polarization conversion can beeffected more efficiently.

Also, in such a construction, the light beam which is notpolarization-converted intactly illuminates the liquid crystal panel 10in a non-polarized state and therefore, a polarizing plate 93 isprovided near the panel. If such a construction is adopted, the partsused in the polarized light converting element array 92 can be decreasedto e.g. a half and the downsizing of the apparatus becomes easy.

The illuminating apparatuses of the above-described Embodiments 2 to 4can also be applied to the liquid crystal projector of FIG. 23.

What is claimed is:
 1. An illuminating apparatus for illuminating asurface to be illuminated, comprising: a condensing optical system forconverting light from a light source into convergent light; acollimating optical system converting said convergent light intoparallel light; and a first convex lens array for receiving saidparallel light; wherein said collimating optical system includes anegative lens which is concave toward the surface to be illuminated. 2.The apparatus according to claim 1, further comprising a polarizationconverting element array for individually converting a plurality oflight beams from said first convex lens array into polarized lights. 3.The apparatus according to claim 1, wherein a surface of said negativelens at the light source side is flat.
 4. The apparatus according toclaim 2, futher comprising a second convex lens array disposed betweensaid first convex lens array and said polarization converting elementarray, with said second convex lens array comprising a plurality ofconvex lenses and each said convex lens corresponding to one of plurallight beams from said first convex lens array.
 5. The apparatus of claim2, further comprising an optical system for overlapping said pluralityof polarized lights from said polarization converting element arraymutually on a surface to be illuminated.
 6. An illuminating apparatusaccording to claim 2, wherein each element of said polarizationconverting element array comprises a polarization splitter, an opticalpath bending mirror and a half wavelength plate.
 7. The apparatus ofclaim 4, wherein an outside diameter of said second lens array and saidpolarization converting element array is smaller than the outsidediameter of said mirror.
 8. The apparatus of claim 4, wherein saidpolarization converting element array includes a plurality ofpolarization converting elements arranged correspondingly to individualconvex lenses of said second convex lens array.
 9. An apparatus,comprising: an illuminating apparatus; at least one display panelilluminated by said illuminating apparatus; and a projection opticalsystem for projecting image light from said illuminated display panel,wherein said illuminating apparatus comprises: a condensing opticalsystem for converting light from a light source into convergent light; acollimating optical system for converting said convergent light intoparallel light; a first convex lens array for receiving said parallellight; wherein said collimating optical system includes a negative lenswhich is concave toward said display panel.
 10. The apparatus accordingto claim 9, further comprising a polarization converting element arrayfor individually converting a plurality of light beams from said firstconvex lens array into polarized lights.
 11. The apparatus according toclaim 10, further comprising a second convex lens array disposed betweensaid first convex lens array and said polarization coverting elementarray, with said second convex lens array comprising a plurality ofconvex lenses and each said convex lens corresponding to one of plurallight beams from said first convex lens array.
 12. The apparatusaccording to claim 9, wherein a surface of said negative lens at thelight source side is flat.
 13. The apparatus according to claim 10,wherein each element of said polarization converting element arraycomprises a polarization splitter, an optical path bending mirror and ahalf wavelength plate.
 14. The apparatus according to claim 9, furthercomprising an optical system for overlapping said plurality of polarizedlights from said polarization converting element array mutually on saiddisplay panel.
 15. The apparatus of claim 11, wherein an outsidediameter of said second lens array and said polarization convertingelement array is smaller than the outside diameter of said mirror. 16.The apparatus of claim 11, wherein said polarization converting elementarray includes a plurality of polarization converting elements arrangedcorrespondingly to individual convex lenses of said second convex lensarray.